Abstract

We obtain the complete and independent bases of effective operators at mass dimension 5, 6, 7, 8, 9 in both standard model effective field theory with light sterile right-handed neutrinos (νSMEFT) and low energy effective field theory with light sterile neutrinos (νLEFT). These theories provide systematical parametrizations on all possible Lorentz-invariant physical effects involving in the Majorana/Dirac neutrinos, with/without the lepton number violations. In the νSMEFT, we find that there are 2 (18), 29 (1614), 80 (4206), 323 (20400), 1358 (243944) independent operators with sterile neutrinos included at the dimension 5, 6, 7, 8, 9 for one (three) generation of fermions, while 24, 5223, 3966, 25425, 789426 independent operators in the νLEFT for two generations of up-type quarks and three generations of all other fermions.

Highlights

  • Describing physical systems below the scale of the new physics, has witnessed great progress in recent years

  • In the νSMEFT, we find that there are 2 (18), 29 (1614), 80 (4206), 323 (20400), 1358 (243944) independent operators with sterile neutrinos included at the dimension 5, 6, 7, 8, 9 for one generation of fermions, while 24, 5223, 3966, 25425, 789426 independent operators in the νLEFT for two generations of up-type quarks and three generations of all other fermions

  • Overall, writing down the higher dimensional operators would be useful to investigate various processes involving in sterile neutrino, especially the baryon and lepton number violation processes, in which new physics effect might be reachable by the future colliders

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Summary

Operators in spinor-helicity formalism

Amplitude-operator correspondence that connects the local on-shell amplitude to the operator producing such amplitude has been extensively used in enumerating operator bases for different kinds of effective field theories [5, 7, 32,33,34,35,36,37]. We present the building blocks and operator basis under circumstances where the neutrinos are Dirac or Majorana type

Spinor helicity amplitudes
Amplitude-operator correspondence
Building blocks
Operator basis
Operator construction using Young tensor
Procedure and example
Lists of operators in νSMEFT
Lists of the dim-5 operators Class FLψ2: 1 type
Lists of the dim-6 operators
Lists of the dim-7 operators Class FL2ψ2: 3 types
Classes involving two-fermions Class FL2ψ2D2: 3 types
Lists of operators in νLEFT
Lists of the dim-5 operators Class FLψ2: 2 types
Lists of the dim-6 operators Class ψ4
Lists of the dim-7 operators Class FL2ψ2: 4 types
Lists of the dim-8 operators
Classes involving six-fermions: ψ6
Conclusion
Full Text
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